The invention relates to a strapping unit for wrapping a tightening strap around a packaged item.
Such a strapping unit has a base plate which is provided with a supporting surface for arranging on a packaged item, the strapping unit furthermore has a tensioning device with which a strap tension can be applied to the tightening strap, for which purpose the tensioning device is provided with an actuable tensioning tool which can be brought into contact with the strap, the tensioning tool being fastened releasably to the strapping unit by at least one fastening means, also has a sealing device, which sealing device is provided with a single- or multi-part sealing tool with which two strap layers can be connected permanently to each other by contact with the strap, the sealing tool being fitted on the strapping unit by at least one releasable, further fastening means, the strapping unit is furthermore provided with a separating means with which the strap can be severed, for which purpose the separating means has a blade which can be brought into contact with the strap, at least part of the separating means being fitted releasably on the strapping unit by at least one further, releasable fastening means.
Strapping units of this type are frequently provided for mobile use so that a user can wrap a steel strap around a packaged item in any desired location. A first generic type of these strapping units typically has a sealing device which produces a connection of two layers of the steel strap by means of multiple notchings, without using an additional sealing element, such as, for example a lead seal. For this type of strapping unit it is also typical for both the strap tension and the formation of a seal to be produced manually without the assistance of outside energy, in particular electric or pneumatic energy. For this purpose, the operator of a strapping unit according to the generic type has only to provide his own muscular power. However, the invention is also suitable for another generic type of strapping unit, in which either a sealing element, such as the already mentioned lead seal, or auxiliary energy, such as, for example, electric or pneumatic energy, is used for producing a welding connection in the case of plastic straps.
However, a common feature of the described generic types of strapping units is that, as a rule, the required strap tension is applied to the strap by means of a rotating tensioning wheel. By means of a frictional lock between the tensioning wheel and the strap layer in contact with it, the strap layer can be moved in the direction of a supply reel of the strap, as a result of which the strap loop becomes smaller and the strap tension consequently becomes greater. Apart from the manually actuated tensioning devices which have already been discussed, tensioning devices which use electric, pneumatic or other auxiliary energy for producing the strap tension can also be provided in strapping units of the generic type.
Virtually all of the components which belong to strapping units of this type and are in contact with the strap are subject to wear. In particular, those components whose function is to act upon the strap, whether by means of friction, a frictional lock or by deformation of the strap, regularly wear out. Consequently, such worn parts have to be regularly replaced. In the case of the described, previously known strapping units, what may not be satisfactory in this connection is that a great maintenance effort is required in order to replace the worn parts.
The invention is therefore based on the object of providing a strapping unit in which worn parts can be swapped with as little maintenance effort as possible.
This object is achieved according to the invention in the case of a strapping unit of the type described at the beginning by it being possible for a plurality of worn parts of the strapping unit to be exchanged using the same, i.e. using just one, tool. According to the invention, fastening means of the worn parts are therefore intended to be of a design, at the points provided for engagement of the tool, which enables the said fastening means to be released and fitted using just one tool in total. According to the invention, it is intended, in particular, for it to be possible at least for the worn parts on the strapping unit to be released with the same tool, swapped for new parts and for the latter to be fastened again using the same tool, wherein it is conceivable that they can be swapped regularly on the one hand, and simultaneously, on the other hand. This may involve one or more worn parts of the sealing device and/or of the separating means. This may, for example, comprise a die-plate and a punch of a notching tool of the sealing device, which tool is provided for sealing a strap loop, and a blade of the separating means. Instead of one of the abovementioned worn parts, or in addition thereto, a tensioning wheel of the tensioning device may also be provided and can likewise be replaced using the same tool.
The invention is therefore based on the concept of simplifying the maintenance effort by reducing the required handling steps and reducing the number of tools to be stocked up on. In the most favorable case, just one single tool which, if possible, is to be a standard tool, is required for the replacement of all of the worn parts. The strapping unit and the tool suitable for it can also be understood to be the maintenance system. Since strapping units are generally used in industrial works in which standard tools of this type are present, virtually all over the world the maintenance work can be undertaken by the user himself. Particularly in the case of mobile, transportable strapping units, this affords the advantage that worn parts can be exchanged very rapidly by the user himself in situ without the service of the unit manufacturer or a workshop being required for this purpose.
The ease of maintaining strapping units according to the invention can be further increased if worn parts or their fastening means on the strapping unit are accessible from the outside. According to the invention, fastening means of the worn parts should be able to be released without other components connected to the corresponding worn part having to be removed for this. For example, coverings or components which are retained or clamped by the same fastening element are connected to the worn part. In particular, components of the strapping unit with which movements of the strapping unit are produced, for example shafts and levers, and which would have to be readjusted again after the swapping of the worn parts should not have to be removed.
In a preferred embodiment, the tool can be just one screwdriver of a certain size, for example of size 4. Of course, other tools could also be provided, such as, for example, a spanner or the like.
Further preferred refinements of the invention emerge from the dependent claims, the description of the figures and the drawing.